The US State Department claims there are signs that the Syrian government may be using chemical weapons, including an alleged chlorine attack on Sunday in northwest Syria.
"We are still gathering information on this incident, but we repeat our warning that if the Assad regime uses chemical weapons, the United States and our allies will respond quickly and appropriately," the department said in a statement.
On Tuesday Maj. Gen. Viktor Kupchishin, the head of the Russian centre for Syrian reconciliation, noted at the daily briefing that terrorists operating in the Idlib de-escalation zone possess significant amounts of poisonous substances with which they fill munitions to use in staged provocations aimed at accusing the Syrian army of "chemical attacks" against civilians.
On Friday, the Russian Defence Ministry said that the Nusra Front* terror group was preparing to stage a false-flag provocation in Syria's Idlib province as a means of framing the Russian Aerospace Forces for attacking civilians with chemical weapons.
The militants were planning to film the alleged poisoning of civilians next to fragments of the Russian munitions so that they could post footage across social platforms and western media outlets, the military added.
Russia has warned multiple times, that the White Helmets group in Syria is responsible for staging provocations with poisonous agents.
In April at least 40 members of the White Helmets organization had admitted during a series of interviews that they staged chemical attacks in Syria to provoke retaliation against President Bashar Assad.
The US and its allies continue to claim that the Syrian government is responsible for a series of the chemical attacks, and particularly one in the city of Douma on 7 April 2018, ignoring emerging evidence that exonerates the Assad regime.
On 13 May the Working Group on Syria, Propaganda and Media made public what they said, was an unpublished report by the OPCW Fact-Finding Mission on the alleged chemical attack in Syria's Douma, indicating that the entire incident was staged.
The Organisation for the Prohibition of Chemical Weapons (OPCW) has not disputed the authenticity of the paper, which was apparently compiled by its own experts, saying that it was conducting "an internal investigation" into its "unauthorised release".
The alleged attack prompted France, the US and the UK, all of whom blamed Damascus for toxic substances use against civilians, to fire over 100 missiles on what they claimed were Syrian government chemical weapons sites.
Weeks prior to the purported incident, both Syria and Russia repeatedly warned of upcoming false flag chemical attacks on Douma, saying that such disinformation campaigns were aimed at covering up terrorists and justifying military action.
*Nusra Front is a terrorist group banned in Russia and many other countries.